This invention relates to the field of surface treatment. Specifically, it relates to surface treatment of airport runways and taxi surfaces, automobile highways, auto racetracks and other surfaces over which vehicles travel which require either initial or periodic surface treatment.
Vehicular surfaces, such as runways and highways, are usually composed of asphalt, concrete or similar type bonded paving materials. Depending upon the application for which the surface is used, certain surface requirements are necessary. For example, a runway surface used for landing and takeoff of airplanes, must have a minimum coefficient of friction in order to permit safe takeoff and landings. The coefficient of friction may be increased by texturing, grooving or otherwise roughening the surface to yield the necessary frictional coefficient. After heavy use, a layer of deposits including rubber scuff marks from tires, petroleum residues and the like build up on the surface reducing the coefficient of friction when the surface is wet. The combination of rubber, petroleum deposits and water promotes hydroplaning of aircraft during takeoff and landing making such operations excessively hazardous.
A related problem is texturing a new surface or a cleaned surface to generate a desired coefficient of friction. It is also desirable to texture a surface prior to repaving or patching it in order to increase the bonding strength between the old surface and the new. Prior methods included texturing a runway when paving utilizing a broom, grooving the surface transversely, or adjusting the paving composition to provide for a high content of aggregate particles at the surface of the pavement. While these texturing techniques can provide initial surface roughness, sacrifices are necessary in terms of ultimate strength of the surface, and further, with the exception of grooving they cannot be used to restore texture to a cleaned surface.
In connection with vehicular surfaces where ice has formed thereon, it is necessary to remove the ice to restore as nearly as possible the dry characteristics of the surface. This is a particular problem in regard to airplane runways since aircraft construction prohibits the use of corrosive deicing chemicals such as sodium or calcium salts. Present techniques include the use of urea, alcohol, glycol mixtures or other noncorrosive eutectics to prevent ice formation. The high cost of these materials and the detrimental effect on the environment constitute drawbacks which suggest the need for alternate ice removal techniques.
In regard to all the areas of surface treatment outlined above, it has been found that the existing methods and devices for accomplishing the desired results have not been satisfactory and, in particular, prior methods of cleaning rubber scuff marks and petroleum deposits from an airport runway and adjacent surfaces have been limited to such methods as chemical treatment, scraping, hydraulic pressure treatment, or cutting the deposits. Alternately the deposits have been grooved transversely to the direction of travel by means of a high speed rotating abrasive wheel to restore frictional contact. This technique is expensive and becomes less effective as the deposits get heavier.
It is accordingly an object of the present invention to provide a method for cleaning rubber, carbon, petroleum residues and like deposits from a vehicular surface to restore its capability for safely handling traffic.
It is a further object of the present invention to provide a method of cleaning a vehicular surface by projecting a particulate material onto the surface with a kinetic energy exceeding the bonding energy between any deposits on the surface and the surface itself.
It is a further object of the present invention to provide a method for cleaning a vehicular surface with particulate material whereby the material is recovered after cleaning for reuse.
It is a further object of the present invention to provide a process for texturing a surface with particulate material to increase the frictional engagement of the surface with vehicles traveling thereon.
It is yet another object of the present invention to texture a vehicular surface by projecting particulate material onto a surface at a velocity sufficient to provide the material with kinetic energy greater than the bonding energy of the surface composition.
It is another object of the present invention to prepare a damaged surface for patching or for resurfacing by particulate blast to roughen the surface to be repaired, thereby to increase the bonding strength between the existing surface and the new surface.
It is another object of the present invention to provide a method for removing sheets or patches of ice from vehicular surfaces by means of a particulate blast to fragment the ice particles for subsequent removal by conventional equipment.
It is a still further object of the present invention to provide a method for fragmenting ice particles on a vehicular surface by projecting particulate material onto the ice with sufficient kinetic or impact energy to fragment the ice for subsequent removal.
These and other objects of the present invention will become apparent from the concluding portion of the specification.
The method disclosed relates to surface treatment. Some existing particulate blast devices can, with modifications, perform the method disclosed herein. For example, in U.S. Pat. No. 3,691,689 to Goff, description is made of a mobile apparatus for cleaning surfaces with a particulate material. In this apparatus the particles are thrown centrifugally at high velocity downwardly onto the surface to be treated. After treatment the particulate material is recovered by means of a brush. Other devices for picking up the spent particulate include magnetic means as described in my copending patent application Ser. No. 432,353, now U.S. Pat. No. 3,858,359, vacuum means as described in a copending application Ser. No. 363,723 assigned to the assignee of the present application, and various other means as described in the following: U.S. Pat. No. 3,034,262 to Paulson, U.S. Pat. No. 3,380,196 to Mabille, and U.S. Pat. No. 3,448,544 to Cardon. While some or all of these prior devices can be adapted to perform the method of the present invention, none of them teaches or discloses the requisite steps for attaining the results desired according to the present invention.